/*
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */
/* 
 * Encodes and decodes to and from Base64 notation.
 *
 * <p>
 * Change Log:
 * </p>
 * <ul>
 *  <li>current - cleaned up by Holger Hoffstaette (holger@codehaus.org) for Mule;
 *  removed System.out/err printing and properly throw IOExceptions from all methods.
 *  <li>v2.1 - Cleaned up javadoc comments and unused variables and methods. Added
 *   some convenience methods for reading and writing to and from files.</li>
 *  <li>v2.0.2 - Now specifies UTF-8 encoding in places where the code fails on systems
 *   with other encodings (like EBCDIC).</li>
 *  <li>v2.0.1 - Fixed an error when decoding a single byte, that is, when the
 *   encoded data was a single byte.</li>
 *  <li>v2.0 - I got rid of methods that used booleans to set options. 
 *   Now everything is more consolidated and cleaner. The code now detects
 *   when data that's being decoded is gzip-compressed and will decompress it
 *   automatically. Generally things are cleaner. You'll probably have to
 *   change some method calls that you were making to support the new
 *   options format (<tt>int</tt>s that you "OR" together).</li>
 *  <li>v1.5.1 - Fixed bug when decompressing and decoding to a             
 *   byte[] using <tt>decode( String s, boolean gzipCompressed )</tt>.      
 *   Added the ability to "suspend" encoding in the Output Stream so        
 *   you can turn on and off the encoding if you need to embed base64       
 *   data in an otherwise "normal" stream (like an XML file).</li>  
 *  <li>v1.5 - Output stream pases on flush() command but doesn't do anything itself.
 *      This helps when using GZIP streams.
 *      Added the ability to GZip-compress objects before encoding them.</li>
 *  <li>v1.4 - Added helper methods to read/write files.</li>
 *  <li>v1.3.6 - Fixed OutputStream.flush() so that 'position' is reset.</li>
 *  <li>v1.3.5 - Added flag to turn on and off line breaks. Fixed bug in input stream
 *      where last buffer being read, if not completely full, was not returned.</li>
 *  <li>v1.3.4 - Fixed when "improperly padded stream" error was thrown at the wrong time.</li>
 *  <li>v1.3.3 - Fixed I/O streams which were totally messed up.</li>
 * </ul>
 *
 * <p>
 * I am placing this code in the Public Domain. Do with it as you will.
 * This software comes with no guarantees or warranties but with
 * plenty of well-wishing instead!
 * Please visit <a href="http://iharder.net/base64">http://iharder.net/base64</a>
 * periodically to check for updates or to contribute improvements.
 * </p>
 *
 * @author Robert Harder
 * @author rob@iharder.net
 * @version 2.1
 */

package org.mule.runtime.core.api.util;

import static org.mule.runtime.core.api.util.IOUtils.closeQuietly;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilterInputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.io.UnsupportedEncodingException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

import org.apache.commons.io.output.ByteArrayOutputStream;

public final class Base64 {

  /* ******** P U B L I C F I E L D S ******** */

  /** No options specified. Value is zero. */
  public static final int NO_OPTIONS = 0;

  /** Specify encoding. */
  public static final int ENCODE = 1;

  /** Specify decoding. */
  public static final int DECODE = 0;

  /** Specify that data should be gzip-compressed. */
  public static final int GZIP = 2;

  /** Don't break lines when encoding (violates strict Base64 specification) */
  public static final int DONT_BREAK_LINES = 8;

  /** Preferred encoding. */
  public static final String PREFERRED_ENCODING = "UTF-8";

  /* ******** P R I V A T E F I E L D S ******** */

  /** Maximum line length (76) of Base64 output. */
  private static final int MAX_LINE_LENGTH = 76;

  /** The equals sign (=) as a byte. */
  private static final byte EQUALS_SIGN = (byte) '=';

  /** The new line character (\n) as a byte. */
  private static final byte NEW_LINE = (byte) '\n';

  /** The 64 valid Base64 values. */
  private static final byte[] ALPHABET;

  private static final byte[] NATIVE_ALPHABET =
      /* May be something funny like EBCDIC */
      {(byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J',
          (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T',
          (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd',
          (byte) 'e', (byte) 'f', (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n',
          (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x',
          (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7',
          (byte) '8', (byte) '9', (byte) '+', (byte) '/'};

  /** Determine which ALPHABET to use. */
  static {
    byte[] bytes;
    try {
      bytes = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".getBytes(PREFERRED_ENCODING);
    } // end try
    catch (java.io.UnsupportedEncodingException use) {
      bytes = NATIVE_ALPHABET; // Fall back to native encoding
    } // end catch
    ALPHABET = bytes;
  } // end static

  /**
   * Translates a Base64 value to either its 6-bit reconstruction value or a negative number indicating some other meaning.
   */
  private static final byte[] DECODABET = {-9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal
      // 0 -
      // 8
      -5, -5, // Whitespace: Tab and Linefeed
      -9, -9, // Decimal 11 - 12
      -5, // Whitespace: Carriage Return
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
      -9, -9, -9, -9, -9, // Decimal 27 - 31
      -5, // Whitespace: Space
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42
      62, // Plus sign at decimal 43
      -9, -9, -9, // Decimal 44 - 46
      63, // Slash at decimal 47
      52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine
      -9, -9, -9, // Decimal 58 - 60
      -1, // Equals sign at decimal 61
      -9, -9, -9, // Decimal 62 - 64
      0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, // Letters 'A' through 'N'
      14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' through 'Z'
      -9, -9, -9, -9, -9, -9, // Decimal 91 - 96
      26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through
      // 'm'
      39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through
      // 'z'
      -9, -9, -9, -9 // Decimal 123 - 126
      /*
       * ,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 127 - 139 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 140 -
       * 152 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 153 - 165 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 166 -
       * 178 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 179 - 191 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 192 -
       * 204 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 205 - 217 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 218 -
       * 230 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 231 - 243 -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9 // Decimal 244 - 255
       */
  };

  // I think I end up not using the BAD_ENCODING indicator.
  // private static final byte BAD_ENCODING = -9; // Indicates error in
  // encoding
  private static final byte WHITE_SPACE_ENC = -5; // Indicates white space in
  // encoding
  private static final byte EQUALS_SIGN_ENC = -1; // Indicates equals sign in

  // encoding

  /** Defeats instantiation. */
  private Base64() {
    super();
  }

  /* ******** E N C O D I N G M E T H O D S ******** */

  /**
   * Encodes up to the first three bytes of array <var>threeBytes</var> and returns a four-byte array in Base64 notation. The
   * actual number of significant bytes in your array is given by <var>numSigBytes</var>. The array <var>threeBytes</var> needs
   * only be as big as <var>numSigBytes</var>. Code can reuse a byte array by passing a four-byte array as <var>b4</var>.
   * 
   * @param b4          A reusable byte array to reduce array instantiation
   * @param threeBytes  the array to convert
   * @param numSigBytes the number of significant bytes in your array
   * @return four byte array in Base64 notation.
   * @since 1.5.1
   */
  private static byte[] encode3to4(byte[] b4, byte[] threeBytes, int numSigBytes) {
    encode3to4(threeBytes, 0, numSigBytes, b4, 0);
    return b4;
  } // end encode3to4

  /**
   * Encodes up to three bytes of the array <var>source</var> and writes the resulting four Base64 bytes to <var>destination</var>
   * . The source and destination arrays can be manipulated anywhere along their length by specifying <var>srcOffset</var> and
   * <var>destOffset</var>. This method does not check to make sure your arrays are large enough to accomodate
   * <var>srcOffset</var> + 3 for the <var>source</var> array or <var>destOffset</var> + 4 for the <var>destination</var> array.
   * The actual number of significant bytes in your array is given by <var>numSigBytes</var>.
   * 
   * @param source      the array to convert
   * @param srcOffset   the index where conversion begins
   * @param numSigBytes the number of significant bytes in your array
   * @param destination the array to hold the conversion
   * @param destOffset  the index where output will be put
   * @return the <var>destination</var> array
   * @since 1.3
   */
  private static byte[] encode3to4(byte[] source, int srcOffset, int numSigBytes, byte[] destination, int destOffset) {
    // 1 2 3
    // 01234567890123456789012345678901 Bit position
    // --------000000001111111122222222 Array position from threeBytes
    // --------| || || || | Six bit groups to index ALPHABET
    // >>18 >>12 >> 6 >> 0 Right shift necessary
    // 0x3f 0x3f 0x3f Additional AND

    // Create buffer with zero-padding if there are only one or two
    // significant bytes passed in the array.
    // We have to shift left 24 in order to flush out the 1's that appear
    // when Java treats a value as negative that is cast from a byte to an
    // int.
    int inBuff =
        (numSigBytes > 0 ? ((source[srcOffset] << 24) >>> 8) : 0) | (numSigBytes > 1 ? ((source[srcOffset + 1] << 24) >>> 16) : 0)
            | (numSigBytes > 2 ? ((source[srcOffset + 2] << 24) >>> 24) : 0);

    switch (numSigBytes) {
      case 3:
        destination[destOffset] = ALPHABET[(inBuff >>> 18)];
        destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
        destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f];
        destination[destOffset + 3] = ALPHABET[(inBuff) & 0x3f];
        return destination;

      case 2:
        destination[destOffset] = ALPHABET[(inBuff >>> 18)];
        destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
        destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f];
        destination[destOffset + 3] = EQUALS_SIGN;
        return destination;

      case 1:
        destination[destOffset] = ALPHABET[(inBuff >>> 18)];
        destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
        destination[destOffset + 2] = EQUALS_SIGN;
        destination[destOffset + 3] = EQUALS_SIGN;
        return destination;

      default:
        return destination;
    } // end switch
  } // end encode3to4

  /**
   * Serializes an object and returns the Base64-encoded version of that serialized object. If the object cannot be serialized or
   * there is another error, the method will return <tt>null</tt>. The object is not GZip-compressed before being encoded.
   * 
   * @param serializableObject The object to encode
   * @return The Base64-encoded object
   * @since 1.4
   */
  public static String encodeObject(Serializable serializableObject) throws IOException {
    return encodeObject(serializableObject, NO_OPTIONS);
  } // end encodeObject

  /**
   * Serializes an object and returns the Base64-encoded version of that serialized object. If the object cannot be serialized or
   * there is another error, the method will return <tt>null</tt>.
   * <p>
   * Valid options:
   * 
   * <pre>
   *              GZIP: gzip-compresses object before encoding it.
   *              DONT_BREAK_LINES: don't break lines at 76 characters
   *                &lt;i&gt;Note: Technically, this makes your encoding non-compliant.&lt;/i&gt;
   * </pre>
   * 
   * <p>
   * Example: <code>encodeObject( myObj, Base64.GZIP )</code> or
   * <p>
   * Example: <code>encodeObject( myObj, Base64.GZIP | Base64.DONT_BREAK_LINES )</code>
   * 
   * @param serializableObject The object to encode
   * @param options            Specified options
   * @return The Base64-encoded object
   * @see Base64#GZIP
   * @see Base64#DONT_BREAK_LINES
   * @since 2.0
   */
  public static String encodeObject(Serializable serializableObject, int options) throws IOException {
    // Streams
    ByteArrayOutputStream baos = null;
    OutputStream b64os = null;
    ObjectOutputStream oos = null;
    GZIPOutputStream gzos = null;

    // Isolate options
    int gzip = (options & GZIP);
    int dontBreakLines = (options & DONT_BREAK_LINES);

    try {
      // ObjectOutputStream -> (GZIP) -> Base64 -> ByteArrayOutputStream
      baos = new ByteArrayOutputStream(4096);
      b64os = new Base64.OutputStream(baos, ENCODE | dontBreakLines);

      // GZip?
      if (gzip == GZIP) {
        gzos = new GZIPOutputStream(b64os);
        oos = new ObjectOutputStream(gzos);
      } // end if: gzip
      else {
        oos = new ObjectOutputStream(b64os);
      }

      oos.writeObject(serializableObject);

      if (gzos != null) {
        gzos.finish();
        gzos.close();
      }

      oos.close();
    } // end try
    catch (IOException e) {
      return null;
    } // end catch
    finally {
      closeQuietly(oos);
      closeQuietly(gzos);
      closeQuietly(b64os);
      closeQuietly(baos);
    } // end finally

    // Return value according to relevant encoding.
    try {
      return new String(baos.toByteArray(), PREFERRED_ENCODING);
    } // end try
    catch (UnsupportedEncodingException uue) {
      return new String(baos.toByteArray());
    } // end catch

  } // end encode

  /**
   * Encodes a byte array into Base64 notation. Does not GZip-compress data.
   * 
   * @param source The data to convert
   * @since 1.4
   */
  public static String encodeBytes(byte[] source) throws IOException {
    return encodeBytes(source, 0, source.length, NO_OPTIONS);
  } // end encodeBytes

  /**
   * Encodes a byte array into Base64 notation.
   * <p>
   * Valid options:
   * 
   * <pre>
   *               GZIP: gzip-compresses object before encoding it.
   *               DONT_BREAK_LINES: don't break lines at 76 characters
   *                 &lt;i&gt;Note: Technically, this makes your encoding non-compliant.&lt;/i&gt;
   * </pre>
   * 
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP )</code> or
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP | Base64.DONT_BREAK_LINES )</code>
   * 
   * @param source  The data to convert
   * @param options Specified options
   * @see Base64#GZIP
   * @see Base64#DONT_BREAK_LINES
   * @since 2.0
   */
  public static String encodeBytes(byte[] source, int options) throws IOException {
    return encodeBytes(source, 0, source.length, options);
  } // end encodeBytes

  /**
   * Encodes a byte array into Base64 notation. Does not GZip-compress data.
   * 
   * @param source The data to convert
   * @param off    Offset in array where conversion should begin
   * @param len    Length of data to convert
   * @since 1.4
   */
  public static String encodeBytes(byte[] source, int off, int len) throws IOException {
    return encodeBytes(source, off, len, NO_OPTIONS);
  } // end encodeBytes

  /**
   * Encodes a byte array into Base64 notation.
   * <p>
   * Valid options:
   * 
   * <pre>
   *              GZIP: gzip-compresses object before encoding it.
   *              DONT_BREAK_LINES: don't break lines at 76 characters
   *                &lt;i&gt;Note: Technically, this makes your encoding non-compliant.&lt;/i&gt;
   * </pre>
   * 
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP )</code> or
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP | Base64.DONT_BREAK_LINES )</code>
   * 
   * @param source  The data to convert
   * @param off     Offset in array where conversion should begin
   * @param len     Length of data to convert
   * @param options Specified options
   * @see Base64#GZIP
   * @see Base64#DONT_BREAK_LINES
   * @since 2.0
   */
  public static String encodeBytes(byte[] source, int off, int len, int options) throws IOException {
    // Isolate options
    int dontBreakLines = (options & DONT_BREAK_LINES);
    int gzip = (options & GZIP);

    // Compress?
    if (gzip == GZIP) {
      ByteArrayOutputStream baos = null;
      GZIPOutputStream gzos = null;
      Base64.OutputStream b64os = null;

      try {
        // GZip -> Base64 -> ByteArray
        baos = new ByteArrayOutputStream(4096);
        b64os = new Base64.OutputStream(baos, ENCODE | dontBreakLines);
        gzos = new GZIPOutputStream(b64os);

        gzos.write(source, off, len);
        gzos.finish();
        gzos.close();
      } // end try
      catch (IOException e) {
        throw e;
      } // end catch
      finally {
        closeQuietly(gzos);
        closeQuietly(b64os);
        closeQuietly(baos);
      } // end finally

      // Return value according to relevant encoding.
      try {
        return new String(baos.toByteArray(), PREFERRED_ENCODING);
      } // end try
      catch (UnsupportedEncodingException uue) {
        return new String(baos.toByteArray());
      } // end catch
    } // end if: compress

    // Else, don't compress. Better not to use streams at all then.
    else {
      // Convert option to boolean in way that code likes it.
      boolean breakLines = dontBreakLines == 0;

      int len43 = len * 4 / 3;
      byte[] outBuff = new byte[(len43) // Main 4:3
          + ((len % 3) > 0 ? 4 : 0) // Account for
                                    // padding
          + (breakLines ? (len43 / MAX_LINE_LENGTH) : 0)]; // New
                                                           // lines

      int d = 0;
      int e = 0;
      int len2 = len - 2;
      int lineLength = 0;
      for (; d < len2; d += 3, e += 4) {
        encode3to4(source, d + off, 3, outBuff, e);

        lineLength += 4;
        if (breakLines && lineLength == MAX_LINE_LENGTH) {
          outBuff[e + 4] = NEW_LINE;
          e++;
          lineLength = 0;
        } // end if: end of line
      } // en dfor: each piece of array

      if (d < len) {
        encode3to4(source, d + off, len - d, outBuff, e);
        e += 4;
      } // end if: some padding needed

      // Return value according to relevant encoding.
      try {
        return new String(outBuff, 0, e, PREFERRED_ENCODING);
      } // end try
      catch (UnsupportedEncodingException uue) {
        return new String(outBuff, 0, e);
      } // end catch

    } // end else: don't compress

  } // end encodeBytes

  /* ******** D E C O D I N G M E T H O D S ******** */

  /**
   * Decodes four bytes from array <var>source</var> and writes the resulting bytes (up to three of them) to
   * <var>destination</var>. The source and destination arrays can be manipulated anywhere along their length by specifying
   * <var>srcOffset</var> and <var>destOffset</var>. This method does not check to make sure your arrays are large enough to
   * accomodate <var>srcOffset</var> + 4 for the <var>source</var> array or <var>destOffset</var> + 3 for the
   * <var>destination</var> array. This method returns the actual number of bytes that were converted from the Base64 encoding.
   * 
   * @param source      the array to convert
   * @param srcOffset   the index where conversion begins
   * @param destination the array to hold the conversion
   * @param destOffset  the index where output will be put
   * @return the number of decoded bytes converted
   * @since 1.3
   */
  private static int decode4to3(byte[] source, int srcOffset, byte[] destination, int destOffset) {
    // Example: Dk==
    if (source[srcOffset + 2] == EQUALS_SIGN) {
      // Two ways to do the same thing. Don't know which way I like best.
      // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6
      // )
      // | ( ( DECODABET[ source[ srcOffset + 1] ] << 24 ) >>> 12 );
      int outBuff = ((DECODABET[source[srcOffset]] & 0xFF) << 18) | ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12);

      destination[destOffset] = (byte) (outBuff >>> 16);
      return 1;
    }

    // Example: DkL=
    else if (source[srcOffset + 3] == EQUALS_SIGN) {
      // Two ways to do the same thing. Don't know which way I like best.
      // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6
      // )
      // | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
      // | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 );
      int outBuff = ((DECODABET[source[srcOffset]] & 0xFF) << 18) | ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12)
          | ((DECODABET[source[srcOffset + 2]] & 0xFF) << 6);

      destination[destOffset] = (byte) (outBuff >>> 16);
      destination[destOffset + 1] = (byte) (outBuff >>> 8);
      return 2;
    }

    // Example: DkLE
    else {
      try {
        // Two ways to do the same thing. Don't know which way I like
        // best.
        // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 )
        // >>> 6 )
        // | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
        // | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 )
        // | ( ( DECODABET[ source[ srcOffset + 3 ] ] << 24 ) >>> 24 );
        int outBuff = ((DECODABET[source[srcOffset]] & 0xFF) << 18) | ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12)
            | ((DECODABET[source[srcOffset + 2]] & 0xFF) << 6) | ((DECODABET[source[srcOffset + 3]] & 0xFF));

        destination[destOffset] = (byte) (outBuff >> 16);
        destination[destOffset + 1] = (byte) (outBuff >> 8);
        destination[destOffset + 2] = (byte) (outBuff);

        return 3;
      } catch (Exception e) {
        // this is not good.
        StringBuilder msg = new StringBuilder(64);
        msg.append(source[srcOffset]).append(": ").append(DECODABET[source[srcOffset]]);
        msg.append(source[srcOffset + 1]).append(": ").append(DECODABET[source[srcOffset + 1]]);
        msg.append(source[srcOffset + 2]).append(": ").append(DECODABET[source[srcOffset + 2]]);
        msg.append(source[srcOffset + 3]).append(": ").append(DECODABET[source[srcOffset + 3]]);
        throw (IllegalStateException) new IllegalStateException(msg.toString()).initCause(e);
      } // end catch
    }
  } // end decodeToBytes

  /**
   * Very low-level access to decoding ASCII characters in the form of a byte array. Does not support automatically gunzipping or
   * any other "fancy" features.
   * 
   * @param source The Base64 encoded data
   * @param off    The offset of where to begin decoding
   * @param len    The length of characters to decode
   * @return decoded data
   * @since 1.3
   */
  public static byte[] decode(byte[] source, int off, int len) {
    int len34 = len * 3 / 4;
    byte[] outBuff = new byte[len34]; // Upper limit on size of output
    int outBuffPosn = 0;

    byte[] b4 = new byte[4];
    int b4Posn = 0;
    int i = 0;
    byte sbiCrop = 0;
    byte sbiDecode = 0;
    for (i = off; i < off + len; i++) {
      sbiCrop = (byte) (source[i] & 0x7f); // Only the low seven bits
      sbiDecode = DECODABET[sbiCrop];

      if (sbiDecode >= WHITE_SPACE_ENC) // White space, Equals sign or
      // better
      {
        if (sbiDecode >= EQUALS_SIGN_ENC) {
          b4[b4Posn++] = sbiCrop;
          if (b4Posn > 3) {
            outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn);
            b4Posn = 0;

            // If that was the equals sign, break out of 'for' loop
            if (sbiCrop == EQUALS_SIGN) {
              break;
            }
          } // end if: quartet built

        } // end if: equals sign or better

      } // end if: white space, equals sign or better
      else {
        throw new IllegalArgumentException("Bad Base64 input character at " + i + ": " + source[i] + "(decimal)");
      } // end else:
    } // each input character

    if (b4Posn > 0) {
      for (i = 0; i < 4 - b4Posn; i++) {
        b4[b4Posn++] = EQUALS_SIGN;
      }
      outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn);
    }

    byte[] out = new byte[outBuffPosn];
    System.arraycopy(outBuff, 0, out, 0, outBuffPosn);
    return out;
  } // end decode

  /**
   * Similar to {@link #decode(String)} only that it will not check the decoded value for GZip compression and thus will not
   * decompress anything
   *
   * @param encodedValue a Base64 encoded value
   * @return a byte array
   * @since 3.7.0
   */
  public static byte[] decodeWithoutUnzipping(String encodedValue) {
    return decode(encodedValue, false);
  }

  /**
   * Decodes the given {@code s}. If the decoded value has a GZip Magic Number header ({@link GZIPInputStream#GZIP_MAGIC}) then it
   * automatically unzips the decoded value
   *
   * @param encodedValue a Base64 encoded value
   * @return a byte array
   */
  public static byte[] decode(String encodedValue) {
    return decode(encodedValue, true);
  }

  private static byte[] decode(String s, boolean unzipIfNecessary) {
    byte[] bytes;
    try {
      bytes = s.getBytes(PREFERRED_ENCODING);
    } // end try
    catch (UnsupportedEncodingException uee) {
      bytes = s.getBytes();
    } // end catch
    // </change>

    // Decode
    bytes = decode(bytes, 0, bytes.length);

    // Check to see if it's gzip-compressed
    // GZIP Magic Two-Byte Number: 0x8b1f (35615)
    if (bytes != null && bytes.length >= 4) {

      int head = (bytes[0] & 0xff) | ((bytes[1] << 8) & 0xff00);
      if (unzipIfNecessary && GZIPInputStream.GZIP_MAGIC == head) {
        ByteArrayInputStream bais = null;
        GZIPInputStream gzis = null;
        ByteArrayOutputStream baos = null;
        byte[] buffer = new byte[4096];
        int length = 0;

        try {
          baos = new ByteArrayOutputStream(4096);
          bais = new ByteArrayInputStream(bytes);
          gzis = new GZIPInputStream(bais);

          while ((length = gzis.read(buffer)) >= 0) {
            baos.write(buffer, 0, length);
          } // end while: reading input

          // No error? Get new bytes.
          bytes = baos.toByteArray();

        } // end try
        catch (IOException e) {
          // Just return originally-decoded bytes
        } // end catch
        finally {
          closeQuietly(baos);
          closeQuietly(gzis);
          closeQuietly(bais);
        } // end finally

      } // end if: gzipped
    } // end if: bytes.length >= 2

    return bytes;
  } // end decode

  /**
   * Attempts to decode Base64 data and deserialize a Java Object within. Returns <tt>null</tt> if there was an error.
   * 
   * @param encodedObject The Base64 data to decode
   * @return The decoded and deserialized object
   * @since 1.5
   */
  public static Object decodeToObject(String encodedObject) throws IOException, ClassNotFoundException {
    // Decode and gunzip if necessary
    byte[] objBytes = decode(encodedObject);

    ByteArrayInputStream bais = null;
    ObjectInputStream ois = null;
    Object obj = null;

    try {
      bais = new ByteArrayInputStream(objBytes);
      ois = new ObjectInputStream(bais);
      obj = ois.readObject();
    } // end try
    catch (IOException e) {
      throw e;
    } // end catch
    catch (java.lang.ClassNotFoundException e) {
      throw e;
    } // end catch
    finally {
      closeQuietly(bais);
      closeQuietly(ois);
    } // end finally

    return obj;
  } // end decodeObject

  /**
   * Convenience method for encoding data to a file.
   * 
   * @param dataToEncode byte array of data to encode in base64 form
   * @param filename     Filename for saving encoded data
   * @since 2.1
   */
  public static void encodeToFile(byte[] dataToEncode, String filename) throws IOException {
    Base64.OutputStream bos = null;

    try {
      bos = new Base64.OutputStream(new FileOutputStream(filename), Base64.ENCODE);
      bos.write(dataToEncode);
    } // end try
    catch (IOException e) {
      throw e;
    } // end catch: IOException
    finally {
      closeQuietly(bos);
    } // end finally
  } // end encodeToFile

  /**
   * Convenience method for decoding data to a file.
   * 
   * @param dataToDecode Base64-encoded data as a string
   * @param filename     Filename for saving decoded data
   * @since 2.1
   */
  public static void decodeToFile(String dataToDecode, String filename) throws IOException {
    Base64.OutputStream bos = null;

    try {
      bos = new Base64.OutputStream(new FileOutputStream(filename), Base64.DECODE);
      bos.write(dataToDecode.getBytes(PREFERRED_ENCODING));
    } // end try
    catch (IOException e) {
      throw e;
    } // end catch: IOException
    finally {
      closeQuietly(bos);
    } // end finally
  } // end decodeToFile

  /**
   * Convenience method for reading a base64-encoded file and decoding it.
   * 
   * @param filename Filename for reading encoded data
   * @return decoded byte array or null if unsuccessful
   * @since 2.1
   */
  public static byte[] decodeFromFile(String filename) throws IOException {
    byte[] decodedData = null;
    Base64.InputStream bis = null;

    try {
      // Set up some useful variables
      File file = FileUtils.newFile(filename);
      byte[] buffer = null;
      int length = 0;
      int numBytes = 0;

      // Check for size of file
      if (file.length() > Integer.MAX_VALUE) {
        throw new IllegalArgumentException("File is too big for this convenience method (" + file.length() + " bytes).");
      } // end if: file too big for int index
      buffer = new byte[(int) file.length()];

      // Open a stream
      bis = new Base64.InputStream(new BufferedInputStream(new FileInputStream(file)), Base64.DECODE);

      // Read until done
      while ((numBytes = bis.read(buffer, length, 4096)) >= 0) {
        length += numBytes;
      }

      // Save in a variable to return
      decodedData = new byte[length];
      System.arraycopy(buffer, 0, decodedData, 0, length);
    } // end try
    catch (IOException e) {
      throw e;
    } // end catch: IOException
    finally {
      closeQuietly(bis);
    } // end finally

    return decodedData;
  } // end decodeFromFile

  /**
   * Convenience method for reading a binary file and base64-encoding it.
   * 
   * @param filename Filename for reading binary data
   * @return base64-encoded string or null if unsuccessful
   * @since 2.1
   */
  public static String encodeFromFile(String filename) throws IOException {
    String encodedData = null;
    Base64.InputStream bis = null;

    try {
      // Set up some useful variables
      File file = FileUtils.newFile(filename);
      byte[] buffer = new byte[(int) (file.length() * 1.4)];
      int length = 0;
      int numBytes = 0;

      // Open a stream
      bis = new Base64.InputStream(new BufferedInputStream(new FileInputStream(file)), Base64.ENCODE);

      // Read until done
      while ((numBytes = bis.read(buffer, length, 4096)) >= 0) {
        length += numBytes;
      }

      // Save in a variable to return
      encodedData = new String(buffer, 0, length, Base64.PREFERRED_ENCODING);
    } // end try
    catch (IOException e) {
      throw e;
    } // end catch: IOException
    finally {
      closeQuietly(bis);
    } // end finally

    return encodedData;
  } // end encodeFromFile

  /* ******** I N N E R C L A S S I N P U T S T R E A M ******** */

  /**
   * A {@link Base64.InputStream} will read data from another <tt>InputStream</tt>, given in the constructor, and encode/decode
   * to/from Base64 notation on the fly.
   * 
   * @see Base64
   * @since 1.3
   */
  public static class InputStream extends FilterInputStream {

    private boolean encode; // Encoding or decoding
    private int position; // Current position in the buffer
    private byte[] buffer; // Small buffer holding converted data
    private int bufferLength; // Length of buffer (3 or 4)
    private int numSigBytes; // Number of meaningful bytes in the buffer
    private int lineLength;
    private boolean breakLines; // Break lines at less than 80 characters

    /**
     * Constructs a {@link Base64.InputStream} in DECODE mode.
     * 
     * @param in the <tt>InputStream</tt> from which to read data.
     * @since 1.3
     */
    public InputStream(java.io.InputStream in) {
      this(in, DECODE);
    } // end constructor

    /**
     * Constructs a {@link Base64.InputStream} in either ENCODE or DECODE mode.
     * <p>
     * Valid options:
     * 
     * <pre>
     *              ENCODE or DECODE: Encode or Decode as data is read.
     *              DONT_BREAK_LINES: don't break lines at 76 characters
     *                (only meaningful when encoding)
     *                &lt;i&gt;Note: Technically, this makes your encoding non-compliant.&lt;/i&gt;
     * </pre>
     * 
     * <p>
     * Example: <code>new Base64.InputStream( in, Base64.DECODE )</code>
     * 
     * @param in      the <tt>InputStream</tt> from which to read data.
     * @param options Specified options
     * @see Base64#ENCODE
     * @see Base64#DECODE
     * @see Base64#DONT_BREAK_LINES
     * @since 2.0
     */
    public InputStream(java.io.InputStream in, int options) {
      super(in);
      this.breakLines = (options & DONT_BREAK_LINES) != DONT_BREAK_LINES;
      this.encode = (options & ENCODE) == ENCODE;
      this.bufferLength = encode ? 4 : 3;
      this.buffer = new byte[bufferLength];
      this.position = -1;
      this.lineLength = 0;
    } // end constructor

    /**
     * Reads enough of the input stream to convert to/from Base64 and returns the next byte.
     * 
     * @return next byte
     * @since 1.3
     */
    @Override
    public int read() throws IOException {
      // Do we need to get data?
      if (position < 0) {
        if (encode) {
          byte[] b3 = new byte[3];
          int numBinaryBytes = 0;
          for (int i = 0; i < 3; i++) {
            try {
              int b = in.read();

              // If end of stream, b is -1.
              if (b >= 0) {
                b3[i] = (byte) b;
                numBinaryBytes++;
              } // end if: not end of stream

            } // end try: read
            catch (IOException e) {
              // Only a problem if we got no data at all.
              if (i == 0) {
                throw e;
              }

            } // end catch
          } // end for: each needed input byte

          if (numBinaryBytes > 0) {
            encode3to4(b3, 0, numBinaryBytes, buffer, 0);
            position = 0;
            numSigBytes = 4;
          } // end if: got data
          else {
            return -1;
          } // end else
        } // end if: encoding

        // Else decoding
        else {
          byte[] b4 = new byte[4];
          int i = 0;
          for (i = 0; i < 4; i++) {
            // Read four "meaningful" bytes:
            int b = 0;
            do {
              b = in.read();
            } while (b >= 0 && DECODABET[b & 0x7f] <= WHITE_SPACE_ENC);

            if (b < 0) {
              break; // Reads a -1 if end of stream
            }

            b4[i] = (byte) b;
          } // end for: each needed input byte

          if (i == 4) {
            numSigBytes = decode4to3(b4, 0, buffer, 0);
            position = 0;
          } // end if: got four characters
          else if (i == 0) {
            return -1;
          } // end else if: also padded correctly
          else {
            // Must have broken out from above.
            throw new IOException("Improperly padded Base64 input.");
          } // end

        } // end else: decode
      } // end else: get data

      // Got data?
      if (position >= 0) {
        // End of relevant data?
        if ( /* !encode && */position >= numSigBytes) {
          return -1;
        }

        if (encode && breakLines && lineLength >= MAX_LINE_LENGTH) {
          lineLength = 0;
          return '\n';
        } // end if
        else {
          lineLength++; // This isn't important when decoding
          // but throwing an extra "if" seems
          // just as wasteful.

          int b = buffer[position++];

          if (position >= bufferLength) {
            position = -1;
          }

          return b & 0xFF; // This is how you "cast" a byte that's
          // intended to be unsigned.
        } // end else
      } // end if: position >= 0

      // Else error
      else {
        // When JDK1.4 is more accepted, use an assertion here.
        throw new IOException("Error in Base64 code reading stream.");
      } // end else
    } // end read

    /**
     * Calls {@link #read()} repeatedly until the end of stream is reached or <var>len</var> bytes are read. Returns number of
     * bytes read into array or -1 if end of stream is encountered.
     * 
     * @param dest array to hold values
     * @param off  offset for array
     * @param len  max number of bytes to read into array
     * @return bytes read into array or -1 if end of stream is encountered.
     * @since 1.3
     */
    @Override
    public int read(byte[] dest, int off, int len) throws IOException {
      int i;
      int b;
      for (i = 0; i < len; i++) {
        b = read();

        // if( b < 0 && i == 0 )
        // return -1;

        if (b >= 0) {
          dest[off + i] = (byte) b;
        } else if (i == 0) {
          return -1;
        } else {
          break; // Out of 'for' loop
        }
      } // end for: each byte read
      return i;
    } // end read

  } // end inner class InputStream

  /* ******** I N N E R C L A S S O U T P U T S T R E A M ******** */

  /**
   * A {@link Base64.OutputStream} will write data to another <tt>OutputStream</tt>, given in the constructor, and encode/decode
   * to/from Base64 notation on the fly.
   * 
   * @see Base64
   * @since 1.3
   */
  public static class OutputStream extends FilterOutputStream {

    private boolean encode;
    private int position;
    private byte[] buffer;
    private int bufferLength;
    private int lineLength;
    private boolean breakLines;
    private byte[] b4; // Scratch used in a few places
    private boolean suspendEncoding;

    /**
     * Constructs a {@link Base64.OutputStream} in ENCODE mode.
     * 
     * @param out the <tt>OutputStream</tt> to which data will be written.
     * @since 1.3
     */
    public OutputStream(java.io.OutputStream out) {
      this(out, ENCODE);
    } // end constructor

    /**
     * Constructs a {@link Base64.OutputStream} in either ENCODE or DECODE mode.
     * <p>
     * Valid options:
     * 
     * <pre>
     *              ENCODE or DECODE: Encode or Decode as data is read.
     *              DONT_BREAK_LINES: don't break lines at 76 characters
     *                (only meaningful when encoding)
     *                &lt;i&gt;Note: Technically, this makes your encoding non-compliant.&lt;/i&gt;
     * </pre>
     * 
     * <p>
     * Example: <code>new Base64.OutputStream( out, Base64.ENCODE )</code>
     * 
     * @param out     the <tt>OutputStream</tt> to which data will be written.
     * @param options Specified options.
     * @see Base64#ENCODE
     * @see Base64#DECODE
     * @see Base64#DONT_BREAK_LINES
     * @since 1.3
     */
    public OutputStream(java.io.OutputStream out, int options) {
      super(out);
      this.breakLines = (options & DONT_BREAK_LINES) != DONT_BREAK_LINES;
      this.encode = (options & ENCODE) == ENCODE;
      this.bufferLength = encode ? 3 : 4;
      this.buffer = new byte[bufferLength];
      this.position = 0;
      this.lineLength = 0;
      this.suspendEncoding = false;
      this.b4 = new byte[4];
    } // end constructor

    /**
     * Writes the byte to the output stream after converting to/from Base64 notation. When encoding, bytes are buffered three at a
     * time before the output stream actually gets a write() call. When decoding, bytes are buffered four at a time.
     * 
     * @param theByte the byte to write
     * @since 1.3
     */
    @Override
    public void write(int theByte) throws IOException {
      // Encoding suspended?
      if (suspendEncoding) {
        super.out.write(theByte);
        return;
      } // end if: supsended

      // Encode?
      if (encode) {
        buffer[position++] = (byte) theByte;
        if (position >= bufferLength) // Enough to encode.
        {
          out.write(encode3to4(b4, buffer, bufferLength));

          lineLength += 4;
          if (breakLines && lineLength >= MAX_LINE_LENGTH) {
            out.write(NEW_LINE);
            lineLength = 0;
          } // end if: end of line

          position = 0;
        } // end if: enough to output
      } // end if: encoding

      // Else, Decoding
      else {
        // Meaningful Base64 character?
        if (DECODABET[theByte & 0x7f] > WHITE_SPACE_ENC) {
          buffer[position++] = (byte) theByte;
          if (position >= bufferLength) // Enough to output.
          {
            int len = Base64.decode4to3(buffer, 0, b4, 0);
            out.write(b4, 0, len);
            // out.write( Base64.decode4to3( buffer ) );
            position = 0;
          } // end if: enough to output
        } // end if: meaningful base64 character
        else if (DECODABET[theByte & 0x7f] != WHITE_SPACE_ENC) {
          throw new IOException("Invalid character in Base64 data.");
        } // end else: not white space either
      } // end else: decoding
    } // end write

    /**
     * Calls {@link #write(int)} repeatedly until <var>len</var> bytes are written.
     * 
     * @param theBytes array from which to read bytes
     * @param off      offset for array
     * @param len      max number of bytes to read into array
     * @since 1.3
     */
    @Override
    public void write(byte[] theBytes, int off, int len) throws IOException {
      // Encoding suspended?
      if (suspendEncoding) {
        super.out.write(theBytes, off, len);
        return;
      } // end if: supsended

      for (int i = 0; i < len; i++) {
        write(theBytes[off + i]);
      } // end for: each byte written

    } // end write

    /**
     * Method added by PHIL. [Thanks, PHIL. -Rob] This pads the buffer without closing the stream.
     */
    public void flushBase64() throws IOException {
      if (position > 0) {
        if (encode) {
          out.write(encode3to4(b4, buffer, position));
          position = 0;
        } // end if: encoding
        else {
          throw new IOException("Base64 input not properly padded.");
        } // end else: decoding
      } // end if: buffer partially full

    } // end flush

    /**
     * Flushes and closes (I think, in the superclass) the stream.
     * 
     * @since 1.3
     */
    @Override
    public void close() throws IOException {
      // 1. Ensure that pending characters are written
      flushBase64();

      // 2. Actually close the stream
      // Base class both flushes and closes.
      super.close();

      buffer = null;
      out = null;
    } // end close

    /**
     * Suspends encoding of the stream. May be helpful if you need to embed a piece of base640-encoded data in a stream.
     * 
     * @since 1.5.1
     */
    public void suspendEncoding() throws IOException {
      flushBase64();
      this.suspendEncoding = true;
    } // end suspendEncoding

    /**
     * Resumes encoding of the stream. May be helpful if you need to embed a piece of base640-encoded data in a stream.
     * 
     * @since 1.5.1
     */
    public void resumeEncoding() {
      this.suspendEncoding = false;
    } // end resumeEncoding

  } // end inner class OutputStream

} // end class Base64
